1. Field of the Invention
The invention relates to a suspension damper device for a bicycle, including a housing adapted to be affixed, on which a suspension means is supported, the suspension means being tensed in a direction of suspension via a damper body of a damping means.
2. Description of the Related Art
From the prior art a variety of suspension damper devices for bicycles are known. For the suspension of a rear swing arm of a bicycle a suspension means is customarily provided which is a pneumatic or steel suspension means in order to absorb impact forces of the rear swing arm occurring during use of the bicycle. In order to control the suspension, in particular to dampen it, a damping means is generally provided.
U.S. Pat. No. 6,360,857 B1 discloses a like suspension damper device. It has a housing which is adapted to be affixed to a bicycle frame and on which an air cylinder is arranged. In this air cylinder, and coaxially with it, a guide rod is arranged which is fixedly connected to the housing and on which a gas piston is slidingly guided in the air cylinder while separating a first air space from a second air space inside the air cylinder. The gas piston is connected to a tubular damper body which in turn is connected by its end portion facing away from the air cylinder to a rear swing arm to be dampened of a bicycle and is displaceable, together with the gas piston, approximately coaxially with the guide rod. Inside the damper body a damper piston is arranged which is fixedly connected to the guide rod and separates a cylinder from an annular space inside the damper body. When the suspension damper device is subjected to an impact, the gas piston is displaced toward the housing via the damper piston, with the gas piston thus reducing an air space delimited by it inside the air cylinder, whereby the impact is cushioned. At the same time the damper body is displaced relative to the damper piston which is fixedly connected to the guide rod, wherein a pressure in the cylinder space is increased. In order to enable a relative displacement between the damper body and the damper piston, two valves are formed inside the damper piston which open starting from a defined pressure difference between the cylinder space and the annular space of the damper body, to thus enable a fluid communication between the cylinder space and the annular space. The first valve of the suspension damper device as a rule opens at comparatively low compression velocities and thus at comparatively low pressure differences in the damper body. From a particular compression velocity the second valve then opens as a kind of overload protection in order to avoid excessively high pressure differences between the cylinder space and the annular space of the damper body.
Here it is a drawback that even at comparatively low pressure differences, bottoming of the suspension damper device may take place, i.e., the gas piston impacts on the housing, which may result in damages. If the valve only opens at comparatively high pressure differences, on the other hand, bottoming will generally be avoided but this may bring about extremely high pressure forces in the damping means, which may also result in damages. In the latter case it is a further drawback that the suspension of the bicycle, in particular the rear swing arm, exhibits a very coarse responsiveness at higher velocities, which may result in loss of traction.
In contrast, the invention is based on the object of providing a suspension damper device which overcomes the named drawbacks.
This object is achieved through a suspension damper device in accordance with the features of claim 1. Further advantageous developments of the invention are subject matter of further subclaims.
In accordance with the invention, a suspension damper device for a bicycle comprises a housing, in particular a housing which is adapted to be affixed to a bicycle frame. On this housing a suspension means may be supported, with this suspension means in particular being a pneumatic suspension means and/or a steel suspension means. The suspension means is adapted to be tensed via a damper body of a damping means in a suspension direction. The damper body is connected to a component to be dampened, for instance a rear swing arm of the bicycle. A damper piston which is affixed to the housing, in particular via a guide rod, is slidingly guided inside the damper body. The damper piston divides the damper body into two damper spaces. For the purpose of damping a suspension of the suspension means by means of the damping means, the latter comprises three valves which are in particular pressure control valves. Through these valves a volume flow of a fluid between the damper spaces may be controlled during tensing of the suspension means in the suspension direction, whereby damping forces of the damping means are in turn controlled. This solution presents the advantage that the valves may open in the presence of different pressure differences between the damper spaces, thus enabling a better adjustment of desired damping forces of the damping device in comparison with the prior art having only two valves. In the event of an impact which is cushioned by the suspension damper device, a valve may then open at low impact velocities, i.e., a low displacement velocity of the damper body, and thus at comparatively low pressure differences between the damper spaces, while the second valve may additionally open at more intense impacts or higher displacement velocities of the damper body, and thus at greater pressure differences. The third valve may then serve as an overload protection and may be opened in addition to the other two valves in the event of very intense impacts and thus very high displacement velocities of the damper body. The second valve thus in particular controls medium and fast displacement movements of the damper body. An opening cross-section of the second valve may be smaller than in the prior art because the third valve additionally opens at extremely high velocities of the damper body in order to allow a high volume flow between the damper spaces so as to decrease the pressure load. As the two valves thus each clear a smaller flow cross-section than in the prior art and only jointly clear a flow cross-section comparable to the prior art, they are each capable of closing comparatively rapidly at the end of the displacement movement of the damper body, with a thrust reversal of the suspension damper device thus taking place extremely quickly.
In a further aspect of the invention the damper piston is arranged on a guide rod which is fastened to the housing, with the damper piston then separating a cylinder space from an annular space inside the damper body, and the valves each control a volume flow of the fluid into the damper body which flows through the damper piston.
In a preferred manner the valves control the volume flow of the fluid during a movement of the damper body in the direction of suspension of the suspension means, i.e., while the suspension means is being tensed. The valves open at different pressure differences between the annular space and the cylinder space. When the pressure again drops below a predetermined pressure difference of a valve, the respective valve closes.
In a preferred manner the first valve comprises an annular valve body which is guided along the guide rod and is tensed via a valve spring against an end face of the damper piston. At a particular pressure difference between the cylinder space and the annular space of the damper body, the valve body is displaced by a pressure of the fluid into an open position away from the damper piston against the resilient force of the valve slides, with the valve body clearing a first connection recess between the cylinder space and the annular space provided in the damper piston. The valve spring is preferably affixed to the guide rod. Such a valve is extremely simple and cost-efficient in terms of construction.
Advantageously the second valve comprises a spring washer which is encompassed by the valve body of the first valve affixed to the guide rod. This spring washer contacts the end face of the damper piston, particularly in the closed condition, and owing to pressure forces of the fluid in the damper body is elastically deformed at a defined pressure difference between the cylinder and annular spaces along sections in a direction away from the damper piston while clearing a second connection recess between the cylinder space and the annular space which is provided in the damper piston. This also is a valve having an extremely simple and cost-efficient construction.
In a preferred manner a guide ring, in particular a hollow-cylindrical guide ring, for guiding the valve body of the first valve is provided, which is affixed to the guide rod. It contacts the damper piston and has a through opening which is in fluid connection with the second connection recess controlled by the second valve. The spring washer of the second valve contacts the guide ring in the closed condition and via the latter controls the second connection recess of the damper piston and the through opening of the guide ring connected to the damper piston. Owing to the guide ring, the first and the second valve may thus be arranged adjacent each other in an extremely compact and space-saving manner.
In a further aspect of the invention, the third valve is a control valve for controlling a flow path of the fluid from the cylinder space to the annular space, wherein the flow path is in particular adapted to be opened and closed.
The pressure forces at which the first or second valve open may be adjusted in a simple manner by altering the number of spring washers allocated to each of them. In addition, or as an alternative, it is also possible to employ spring washers having different mechanical properties, for example having a different elasticity.
In order to ensure a spacing of the spring washers of the first and the second valve, the annular valve body of the first valve advantageously comprises a support shoulder extending away from the damper piston via which the spring washer allocated to it is then supported.
In order to enable a flow of fluid from the cylinder space to the annular space in the opened condition of the second valve, at least one through opening is provided in the support shoulder of the annular valve body of the first valve.
In order to increase a volume flow between the cylinder space and the annular space in the opened condition of the first and the second valve, at least one flow recess is provided between an outer jacket surface of the guide ring and an inner jacket surface of the annular valve body of the first valve. This flow recess may simply be executed as a longitudinal groove in the inner jacket surface of the annular valve body.
In accordance with the invention, a suspension damper device comprises a housing which is adapted to be affixed and against which a suspension means may be supported. The latter may be tensed via a damper body of a damping means that is adapted to be connected to a component to be dampened. The damper body comprises a damper piston which is adapted to be affixed to the housing while physically separating two damper spaces inside the latter. Through the intermediary of a valve a fluid connection between the damper spaces may be controlled, with the valve being adapted to be opened and closed via a lever which is arranged on the housing and may be pivoted relative to the housing. Advantageously the valve is opened fully when the lever extends about in parallel with a longitudinal direction of the suspension damper device.
This solution has the advantage that an operator of the lever, such as a rider of a bicycle equipped with the suspension damper device, may clearly ascertain whether the valve is opened fully. In the prior art, on the other hand, such a lever has an oblique arrangement relative to the longitudinal direction of the suspension damper device both in the opened condition of a valve and in a closed condition of a valve, so that it may be difficult for an operator of the lever to know whether the valve to be controlled by the lever is presently opened or closed.
In a preferred manner the damper piston is affixed to the housing via a guide rod while separating an annular space penetrated by the guide rod from a cylinder space inside the damper body, wherein a volume flow of a fluid from the cylinder space in a direction toward the annular space of the damper piston may be controlled by means of the lever.
In accordance with the invention, a suspension damper device for a bicycle comprises a housing which is adapted to be affixed and on which a suspension tube of a pneumatic suspension means is fixedly arranged. Inside the suspension tube a gas piston is guided for pneumatic suspension, which is adapted to be displaced in the suspension tube via a damper body of a damping means which is adapted to be connected to a component to be dampened such as, e.g., a rear swing arm. For the pneumatic suspension the gas piston jointly with the suspension tube defines an air space, wherein advantageously a volume of the air space is determined by the size of a spacer which is adapted to be affixed to the housing and is arranged inside the air space. This allows to vary the volume of the air space by way of the size of the employed spacer during assembly. In the prior art, on the other hand, the size of the air space is disadvantageously determined through differently dimensioned suspension tubes. In order to save space, the spacers may be executed to be hollow or of closed-cell plastic. With the aid of the spacer a cushioning characteristic line of the suspension damper device may thus be adapted in a simple manner to desired conditions of use of the suspension damper device.